Progress Report Oct 17, 2018

Dear Dialog,

This week, I will be updating you, for the first time, on how research has been going! My research will consist of relating melt pools, and their characteristics, on Mars to melt pools seen on other planetary bodies within the solar system, such as Venus, the Moon, and Mercury. The investigation will help elucidate whether there exists a correlation between melt distribution, topography, impactor size, amount of melt, and/or impactor angle. To do this, I am using isis photogrammetry software, QGIS, and ArcGIS to process surface images and map the pools proximal to the outer crater rims. 

I first needed to understand what melt pools looked like before I could map them. They are melt from the impact that has flowed over the rim and pooled in the low topography areas. Similar to lakes that form on mountains from snow/rain run-off. Lots of areas will have gotten wet at some point, but the water will tend to collect into lower potential areas. These melt pools have shown interesting features. On the moon, there is a strong inverse correlation to impactor angle and direction of flow. Whereas on Venus, there is not a significant correlation. So investigating the Martian flows will be the next step towards understanding the further out bodies of the solar system, including icy bodies. Part of what makes Mars unique in particular is the fact that it has an atmosphere. This facilitates aeolian processes. Dust is a large part of the Martian environment and covers most of the surface, at least to some extent. This dust can often lie on top of the melt pools, obscuring them making their identification difficult. More on this topic in future posts.

So far, my research has consisted of establishing my environment and troubleshooting different softwares. Let me walk you through them! The isis software, stumped me for a little while. I tried accessing it on a Windows machine, installing cygwin in order to run bash commands, which is a requirement for isis. But this led to a dead end after exhausting possibilities of broken scripts/pathways and subsequently reading that isis runs on Mac OS. Moving on to the Mac mini, I tried reading through the maual looking for a way to run isis. Initially, I had to add where the path of isis was to the .bash_profile file located locally on my account so I could run isis from Terminal fluidly. Then, I had it in my head that I would need to enter, so to speak, the program much like python within Terminal, where one executes the name and then the program is accessible. This was not the case. The proper way to access the software is simply by typing the command into Terminal along with any needed parameters. Hurdle crossed. 

Onto processing! The images need to be found on source websites. After attempting to create a project on Mars around Resen crater for practice, I was informed courteously by Catherine that the "melt" I had mapped was, in fact, very wrong. We took it step back and decided to map some pools on the Moon since they are easy to identify due to a lack of erosional processes. To do this here is the process:

Access Jmars or the Lunar Orbital Data Explorer website to find the images you would like. Investigation included looking at LRO NAC and LRO LOLA data(process still in progress). Download the .img and .lbl files. Run the following commands:

$ cd /homePaths/GISProjects/{projName}/Preprocessing/

$ lronac2isis

> Input: M103831840LE.IMG 

> Output: M103831840LE.cub

> Run

$ spiceinit from=M103831840LE.cub

$ lronaccal

> FROM: M103831840LE.cub

> TO: M103831840LE_cal.cub

> Uncheck all defaults for now

> Run

$ cam2map 

> FROM: M103831840LE_cal.cub

> MAP: $base/templates/maps/sinusoidal.map

> TO: M103831840LE_cal_cam.cub

> MATCHMAP: Don’t check “Match the map file”

> Output Map Resolution: Compute resolution from input cube (CAMERA)

> Output Map Ground Range: Minimize output image size

> Run

Ta-da! You should have a GIS-friendly .cub file now. Now we can open QGIS (or ArcMap if you move the files to a Windows computer) and create a new project. Define the Coordinate Reference System, CRS, to be "Moon 2000". Then Add Layer > Raster > {yourMoonImage}.cub. Check Properties to make sure the image is also in the Moon 2000 CRS. Next, verify the Draw Freehand tool is available. If not, Plug-Ins > Manage > Search for "Freehand" > Add > Close. Now we need to add LOLA data, but TBD. We also need to create a few shapefiles. Add Layer > New Shapefile > Polygon> Name it "meltPools". In the bottom left, where the loaded files are shown, Left Click meltPools > Toggle Editing. Now we can start drawing what we think are melt pools! Below are two examples of craters with melt pools drawn from LRO NAC images.

A very conservative mapping of Image M103831840LE:

The melt/flows are shown in blue. A large portion of this image could be melt, including venier. Only the most blatant flows/melt have been marked.

The melt/flows are shown in blue. A large portion of this image could be melt, including venier. Only the most blatant flows/melt have been marked.

From the eastern rim of Tycho Crater Left and Right:

Here we see the melt denoted in mauve. There is also strong indicators of melt, including colling cracks and albedo changes where the pools are located.

Here we see the melt denoted in mauve. There is also strong indicators of melt, including colling cracks and albedo changes where the pools are located.

#TODO next will be to nail down how to process the LOLA data and incorporate it into GIS projects. From there, I can start working on Martian melt.

-W